1. Field of the Invention
The present invention pertains to a method for porosity determination in porous media, such as are encountered in petroleum engineering and related earth science studies, by x-ray computed tomography (CT).
2. Background
X-ray methods such as shadow graph techniques to study oil recovery possibilities in core samples under laboratory conditions are known. Moreover, with the development of computed tomography (CT) a distinct cross-sectional image or "a slice" may be obtained through an object. U.S. Pat. No. 4,663,711 to Vinegar et al describes a method for modeling flooding of a petroleum reservoir using computed tomography wherein x-rays of two different energy levels are applied to a core sample and at least one of the fluids injected in the core sample is doped with a strong photoelectric absorbing material. Multiple scans are conducted at the two energy levels during the displacement process and the resulting data permit calculation of the oil, water, and gas phase saturations of the core. However, it is also important in the development of petroleum resources and other activities to be able to determine the porosity of a porous media, as well as determine the extent of saturation of the media with a certain composition or compositions and the relative permeability of certain media.